Profile components of fiber composite materials and process and apparatuses for their continuous production are, in principle, known from prior art. Such profile components are used in a wide variety of areas of engineering. This includes reinforcement profiles of all kinds used to build aircraft fuselages or boat hulls according to the principles of light-weight construction, for example standard design profiles such as pipes, profiled beams, and solid or flat profiles, in addition to functional profile components such as wheel control or leaf spring elements.
In particular, simple standard profiles with a straight, unchanging cross section over the profile length have been produced for a long time, usually using traditional pultrusion processes. To this end, batches of continuous reinforcing fibers are generally first impregnated with a resin matrix and then drawn through a molding die that corresponds to the profile cross section. The impregnated fiber bundle thereby takes on the form of the die profile, and is cured in this form by a heating element directly following the nozzle.
Known pultrusion systems and processes produce continuous profiles in this manner, which can be wound onto drums or cut to length after curing. Typical pultrusion products are round, flat or corner profiles that can be either hollow or made out of solid material. In pultrusion, non-unidirectional woven-fabric structures can also be incorporated to a limited extent, for example by feeding layers of fabric to the molding die together with the unidirectional reinforcing fibers.
However, pultrusion processes are principally limited to the manufacture of unidimensional, linear or straight profiles. This limitation applies as a rule with only a few exceptions, in which it is possible to produce slightly curved pultrusion profiles. However, these profiles, in turn, are subject to additional limitations in terms of the producible profile cross sections.
In any case, however, the known pultrusion processes are limited to producing profiles with a smooth, even profile surface and at the same time, with an unvarying profile cross section along the entire length of the profiles. Both profiled surfaces of any kind, and a cross-sectional form or cross-sectional area that is somewhat variable over the length of the profile generally cannot be produced using pultrusion processes. Likewise, pultrusion processes do not allow profile characteristics that vary over the length of the profile such as are generally needed to introduce force in the form of reinforced force introduction points or inserts for force application in the case of complex applications.
This means that reinforcements or inserts of this kind can, at best, be added to a finished pultrusion profile later, for which time-consuming reworking is required and which may be accompanied by a possible weakening of the fiber structure or of the fiber cohesion.
Last but not least, the quality of the finished carbon fiber composite profile that can be achieved using the known pultrusion processes is limited, among other things due to the lack of a defined pressing process when the impregnated fiber bundle passes through the molding die. In particular, the production of profile components with a high reinforcement/matrix volume ratio with concomitant minimal air entrapment and high dimensional stability, which is generally required for demanding applications, is difficult or nearly impossible to achieve using the known pultrusion methods.
Due to the described limitations of the known pultrusion methods, components that are demanding both in terms of their shape and material properties are therefore still subject to time-consuming, individual production using conventional lamination methods, possibly from prepregs, or by means of resin transfer molding or pot molding.
Since the latter methods are usually limited to comparatively small components that are not very mechanically resilient, the complex layered production of profiles and components from prepregs with subsequent pressing and curing until the finished component is obtained has, until now, been the only option for especially demanding functional or profile components. The cycle times for producing one component are accordingly long and the associated production costs are accordingly high.
A method and a device for the continuous production of stringer profiles are known from patent DE 10 2008 041 832 A1, wherein continuous fiber strands or webs are enclosed between rotary forming chains, impregnated with matrix material and cured. This process and the associated apparatus known from prior art are limited, however, to the production of straight, prismatic profiles. Neither curved profiles, nor profiles with a variable profile cross section or variable surface contour can be produced therewith, nor can profiles with local reinforcements and/or other profile characteristics that vary over the length of the profile be produced, for example locally reinforced force-application points or inserts.